Ultrafast Interatomic Electronic Decay in Multiply Excited Clusters

An ultrafast mechanism belonging to the family of interatomic Coulombic decay (ICD) phenomena is proposed. When two excited species are present, an ultrafast energy transfer can take place bringing one of them to its ground state and ionizing the other one. It is shown that if large homoatomic clusters are exposed to an ultrashort and intense laser pulse whose photon energy is in resonance with an excitation transition of the cluster constituents, the large majority of ions will be produced by this ICD mechanism rather than by two-photon ionization. A related collective-ICD process that is operative in heteroatomic systems is also discussed.

Figure 1

Schematic representation of the process. (a) Two subunits of the system are excited by absorbing two photons. (b) One of the constituents of the system deexcites transferring the energy to the neighbor which uses it to emit its excited electron.

Figure 2

Ab initio computed total ICD width $\Gamma$ for the system ${\mathrm{Ne}}^{*}(2p^{-1}3s)\mathrm{\text{−}}{\mathrm{Ne}}^{*}(2p^{-1}3s)$ compared to the prediction of the virtual-photon model, Eq. (1). The atomic fluorescence decay width is indicated by a horizontal line, while the equilibrium interatomic separation by a vertical one. Note the double logarithmic scale used.

Figure 3

Schematic representation of the collective process discussed in the text for heteroatomic clusters. Two constituents of the system deexcite simultaneously transferring the energy to a third species and ionizing it.